Jump to main content.

Radon

Contact Us**Search:**All         EPAThis         Area

    - You are here:  EPA Home
    - Air
    - Indoor Air
    - Radon
    - Publications
    - Measurement Device Protocols

----

# "Indoor Radon and Radon Decay Product Measurement Device                 Protocols"

Note: EPA no longer updates this information, but it may be useful as a reference or resource.

U.S. EPA, Office of Air and Radiation (6604J)EPA 402-R-92-004, July 1992

**Contents**
    - Disclaimer
    - Acknowledgements
    - Significant Changes in This Revision
    - Radon and Radon Decay Product Measurement Methods

**Section 1:  General Considerations**
| 1.1 | Introduction and Background                                                                                    |
|-----|----------------------------------------------------------------------------------------------------------------|
| 1.2 | General Guidance on Measurement Strategy, Measurement Conditions, Device Location Selection, and Documentation |
| 1.3 | Quality Assurance                                                                                              |

**Section 2:  Indoor Radon Measurement Device Protocols**
| 2.1 | Protocol for Using Continuous Radon Monitors (CR) to Measure Indoor Radon Concentrations                                                                                                    |
|-----|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| 2.2 | Protocol for Using Alpha Track Detectors (AT or ATD) to Measure Indoor Radon Concentrations                                                                                                 |
| 2.4 | Protocol for Using Activated Charcoal Adsorption Devices (AC) to Measure Indoor Radon Concentrations                                                                                        |
| 2.5 | Protocol for Using Charcoal Liquid Scintillation (LS) Devices to Measure Indoor Radon Concentrations                                                                                        |
| 2.6 | Protocol for Using Grab Radon Sampling (GB, GC, GS), Pump/Collapsible Bag Devices (PB), and Three-Day Integrating Evacuated Scintillation Cells (SC) to Measure Indoor Radon Concentrations |
| 2.7 | Interim Protocol for Using Unfiltered Track Detectors (UT) to Measure Indoor Radon Concentrations                                                                                           |

**Section 3:  Indoor Radon Decay Product Measurement Device Protocols**
| 3.1 | Protocol for Using Continuous Working Level Monitors (CW) to Measure Indoor Radon Decay Product Concentrations                 |
|-----|--------------------------------------------------------------------------------------------------------------------------------|
| 3.2 | Protocol for Using Radon Progeny Integrating Sampling Units (RPISU or RP) to Measure Indoor Radon Decay Product Concentrations |
| 3.3 | Protocol for Using Grab Sampling-Working Level (GW) to Measure Indoor Radon Decay Product Concentrations                       |
    - Glossary
    - References
    - List of Exhibits           - 2-1 - Radon Correction Factors
      - 3-1 - Kusnetz Factors 

**Please Note:**

EPA closed its National Radon Proficiency Program (RPP) in 1998.  The information in this document which refer to companies, individuals or test devices that "meet EPA's requirements", or "EPA Certified...",  or refers to EPA's old RPP designations "RMP or RCP" is no longer applicable.  Please check ourproficiency page for more information on how to find a qualified radon service professional.

**Disclaimer**
> 
While we try to keep the information timely and accurate, we make no expressed or implied guarantees.  We will make every effort to correct errors brought to our attention. The material and descriptions compiled for these pages are not to be considered Agency guidance, policy, or any part of any rule-making effort but are provided for informational and discussion purposes only. They are not intended, nor can they be relied upon, to create any rights enforceable by any party in litigation with the United States.

**Acknowledgements**
> 
This document represents the cumulative efforts of many dedicated individuals within the radon measurement community and the U.S. Environmental Protection Agency.  Several key components of this document were prepared by the authors acting as interpreters of the substantial field experience and technical knowledge provided by these individuals, and their assistance is gratefully acknowledged.

**Significant Changes in this Revision**
> 
This protocol document updates and supersedes the U.S. Environmental Protection Agency (EPA) document entitled, "Indoor Radon and Radon Decay Product   Measurement Protocols," and issued in March, 1989 (U.S. EPA 1989a).  The updating reflects new information, new procedures, and new measurement devices,   including a new interim protocol for unfiltered track detectors.  The EPA's testing recommendations are summarized in 		Section 1.2.    This measurement strategy reflects the changes made in the most recent edition of "A Citizen's Guide to Radon"  More information   is also provided in the EPA measurement guidance document, "Protocols for Radon and Radon Decay Product Measurements in Homes" (U.S. EPA 1992c).  Guidance   on radon measurements in schools and for real estate transactions is also available (U.S. EPA 1989b, 1992b).  This edition contains some clarifications and new information   on quality assurance.  The addition of a Glossary provides definitions and formulas for several of the technical terms used in the document,   including accuracy, precision, and the values used to quantify these parameters.  The two previous editions of these protocols (U.S. EPA 1986, 1989a) used the value   coefficient of variation (COV), defined as the standard deviation divided by the mean, as the expression used for the goal (at 4 pCi/L or 0.02 WL) of 10 percent for   precision.  The COV should decrease with increasing concentration.  This edition explains that there is a variety of ways to calculate and express precision, including   the COV and the relative percent difference, defined as the difference between two duplicates divided by their mean.  It is important to monitor precision over the entire   range of radon levels that are encountered routinely in the measurement program, and that a systematic and documented method for evaluating changes in precision be part   of the standard operating procedures.  While a limited precision error is desirable (e.g., COV of		< 10% at 4 pCi/L), it is most important to maintain the total   error of any individual device (including both errors in precision and accuracy) to within ± 25 percent of the "true" radon or decay product concentration   for concentrations at or above 4 pCi/L (0.02 Working Levels when the equilibrium ratio is 0.5).

To limit errors in accuracy, this edition recommends that users calibrate their measurement systems at least once every 12 months.  Participation in the former National   Radon Measurement Proficiency (RMP) Program did not satisfy the need for annual calibration, as this Program was a performance test, not a calibration procedure.  The 1986   and 1989 versions of the measurement protocols recommended that known exposure measurements, or spikes, be conducted at a rate of a few percent of the total number of   measurements.  These measurements are those for which the detectors are exposed to a known radon concentration in a calibration chamber and analyzed routinely. The   results are used to monitor the accuracy of the entire system.  This edition clarifies this recommendation, specifying that spikes be conducted at a rate of three per   100 measurements, with a minimum of three per year and a maximum required of six per month.  This reduces the number of spikes necessary for large users and clarifies   the need for spikes by all users.  A significant change in this version of the Measurement Protocols is the requirement that all devices used for measurements in homes,   schools, or workplaces be deployed for a minimum of 48 contiguous hours.  It is important to understand that this minimum measurement period applies to all cases when   the result of the measurement is given to a homeowner or building official to determine the need for further measurements or remedial action.  The exceptions to the 48-hour   measurement period are for those cases when the results will not be reported to a homeowner or building official, but will be used by a mitigator or researcher within the   context of their project or research.  For example, in-progress diagnostic measurements made in the process of performing mitigation can help to determine points of radon   influx.  Results of these measurements will be used to assist the contractor to better understand the dynamics of radon within that building, and will be part of a series   of measurements, including pre- and post-mitigation 48-hour measurements.  Radon researchers testing the effects of mitigation techniques, measurements methods, or strategies   may also need to perform measurements of flexible durations.  The Agency has implemented a requirement for a minimum measurement period for several reasons.  First, it will   help ensure consistency among measurement programs, thereby ensuring that measurement results of at least a minimum quality become the basis for decisions by homeowners,   school officials, and others responsible for authorizing further measurements or mitigation.  This will become increasingly important as radon is measured in more and   different types of buildings, and as a more diverse group of people, many without technical backgrounds, find the need to compare and understand these results.  Second,   a minimum measurement period will guarantee that a certain number of hours, including daily radon cycles, will be incorporated into the result reported to the persons   responsible for making a decision about that building.

A period of 48 hours for the minimum measurement period is a policy decision that was arrived at after careful scrutiny of the possible options.  It is important that   the complete measurement result includes the effects of daily fluctuations in radon levels, so the minimum period needed to be a multiple of a 24-hour day.  The Agency   deems a single 24-hour period as too short because of the possibility of unforeseen circumstances occurring during the 24 hours; this possibility is diminished if two   24-hour periods form the duration of the measurement.  One possible unforeseen circumstance is the improper implementation of closed-building conditions.  A longer   measurement period increases the chance of identifying such occurrences and helps minimize their impact.  Finally, it was deemed important to include two daily cycles   so that periods of low and high radon concentrations are well represented in the overall result.  There may be some situations when it is impossible to terminate the   measurement at exactly 48 hours; therefore, a grace period of two hours will be allowed.  A measurement made over a period of at least 46 hours is sufficient and is   considered a two-day measurement.  This grace period applies to all measurement methods.  Concerns have been raised regarding the requirement of a minimum distance of   30 inches from the floor for placement of detectors.  The change from 20 inches to 30 inches was made in the March 1989 Protocols (U.S. EPA 1989a).  This distance is   not thought to be critical, so this version again recommends a minimum distance of at least 20 inches. In addition, the 1989 edition was not specific regarding the   minimum distance between the measurement location and an exterior wall; this revision clarifies that distance to be about one meter, or three feet.  Suspended detectors   should also be about six to eight feet above the floor (i.e., within the general breathing zone).  		Sections 2.6   (Evacuated Scintillation Cells), 2.7 (Pump/Collapsible Bags), and 		2.8 (Radon Grab Sampling) of the previous   protocol document (U.S. EPA 1989a) describe methods that share common features.  For this reason, the three measurement methods are combined into one section in this revision.    In addition, the Appendices A and B of the previous document are now part of their corresponding protocols.  The radon grab sampling and pump/collapsible bags methods are not   appropriate for purposes of determining the need for further measurements or for mitigation because they do not comply with the 48-hour minimum measurement period.    This revision also reflects the method designations used in the former National Radon Proficiency (RPP) Program. A two letter code for each method has been adopted,   although ATDs (AT), RPISUs (RP), and EICs/ECs (ES or EL) may still be referred to by their traditional acronyms.  The current designations are as follows:

**Radon and Radon Decay Product Measurement Methods**
| **METHOD CATEGORY**                                                                                              | **Abbreviations**        |
|------------------------------------------------------------------------------------------------------------------|--------------------------|
| **Common Designation**                                                                                           | **Protocol Designation** |
| Continuous Radon Monitors                                                                                        | CRM                      | CR |
| Alpha Track Detectors                                                                                            | ATD                      | AT |
| Electret Ion Chambers  Short Term  Long Term                                                 | EIC/EC                   | ESEL |
| Activated Charcoal Adsorption Devices(formerly called charcoal canisters)                                        | CC                       | AC |
| Charcoal Liquid Scintillation                                                                                    | CLS                      | LS |
| Three-day Integrating Evacuated Scintillation Cells                                                              |                          | SC |
| Pump/Collapsible Bag Devices(24 hour sample)                                                                     |                          | PB |
| Grab Radon Sampling  Scintillation Cells  Activated Charcoal  Pump-Collapsible Bag |                          | GSGCGB |
| Unfiltered Track Detectors                                                                                       | UTD                      | UT |
| Continuous Working Level Monitors                                                                                | CWLM                     | CW |
| Radon Progeny Integrating Sampling Units                                                                         | RPISU                    | RP |
| Grab Sampling - Working Level                                                                                    |                          | GW |

Go to Section One

Top of page

About the Indoor Environments Division |     Where You Live  | Ask the Radon Expert |     Site Index

----

### Local Navigation

    - Radon Home
    - Where You Live
    - A to Z Site Index
    - Frequent Questions
    - Glossary
    - Publications
    - Related Links
    - National Radon Action Month
    - Radon Health Risks
    - Who Can Test or Fix Your Home for Radon?
    - Radon and Real Estate
    - Radon Resistant New Construction (RRNC)
    - EPA Map of Radon Zones
    - Radon in Drinking Water
    - State Indoor Radon Grants (SIRG)
    - Kids, Students and Teachers
    - Hotlines
    - TV and Radio Ads

----

    - EPA Home
    - Privacy and         Security Notice
    - Contact Us

Jump to main content.